This invention relates in general to digital networks and more specifically to checking server status by using health probe chaining.
Collections of computers are used for many different applications such as in business, education, entertainment, and for recreational and other uses. These collections can include hundreds, thousands or more, separate computers or other digital processing devices. One type of popular arrangement includes many server computers referred to as a “server farm” for providing World Wide Web (“web”) services over the Internet. Such web services can include serving web pages, processing transactions, performing database searches, etc.
In order to ensure that a large collection of servers is operating properly it is important to detect when a server computer becomes inoperable or otherwise malfunctions. This can be accomplished by intermittently checking the status of each server. One detection approach uses “keepalive” signals or “health probes.” These signals can be various types of communications such as messages that are sent by a central device, such as a load balancer, to each server in the collection. When a server receives the health probe it responds to the load balancer so that the load balancer can assume that the responding server is operating properly. However, one drawback of this approach is that health probing can be a resource intensive task depending on the number of servers to check and the frequency of sending the health probes and processing the returned data.